1. Field of the Invention
The present invention relates generally to a three-dimensional warehouse for warehousing articles and is, more particularly, suitable for a large-scale warehouse for dealing with a good deal of various commercial goods.
In a conventional 3-D warehouse, housing articles such as commercial goods, etc. are housed in storage blocks (racks) provided on a vertical plane. FIG. 18 partially illustrates one example of the conventional 3-D warehouse described above. Shown is a stacker crane having an elevator 4 vertically movable along a perpendicular rail 3 provided on a stage 1 movable on a rail 2 through which entrance/delivery stations A, B are connected. This elevator is, as will be mentioned later, equipped with a fork or the like (not shown) required for transferring the articles. Conveyors (not shown) for conveying pallets loaded with article cases are laid in the vicinities of the stations A, B. For instance, fifty pieces of corrugated paper boxes as one unit are loaded on the pallet and then conveyed.
In the three-dimensional (3-D) warehouse described above, when the pallet reaches the entrance station via the conveyor, the pallet is shifted onto the station from the conveyor. Subsequently, an empty pallet rack position for taking in the goods is designated by a control unit. Then, the stacker crane moves to the entrance station from the entrance rack position of the last time. (Generally, a standby state implies that the crane remains in the station position till the next indication is given in the case of taking in the goods.) The transfer of the designated pallet from the station to the stacker crane is completed in a position of the entrance station by means of the fork installed in the stacker crane. Then, this stacker crane moves to the designated empty pallet rack position, where the pallet is retransferred in the pallet rack by the fork of the stacker crane. A control computer is thereby informed of the fact that this pallet rack has been housed in the indicated position. As explained above, the stacker crane goes back to the position of the entrance station and waits there. Such operations are repeated.
In the case of this example, a moving range of the stacker crane is defined by points A, E, F, B, wherein the points E, F are set above the points A, B. Further, the pallet racks are provided on both surfaces or one surface of this plane AEFB.
The articles, which are thus taken out, form groups of the same articles according to an order unit. Cases of the same articles are grouped by use of a device called a case flow rack (not shown) and thereafter sorted by a device known as a sorter.
FIG. 19 shows one example of a conventional bring-in conveyor to the sorter. Sorting chutes 6a-6n having inclined surfaces are arrayed on both sides of the rectilinear conveyor 5. Each chute is allocated to a specified article. The articles are distributed to desired positions by removing a stopper, provided corresponding to a moving position of the conveyor 5, for stopping a drop.
FIG. 20 illustrates conveyors for conveying the articles distributed from the sorter shown in FIG. 19 towards a discharge port. Laid on both sides of the chute are two lines of carrier conveyors 7a, 7b and discharge conveyors 8a, 8b connected thereto. The articles are taken out of the tip parts thereof.
The delivery operation has hitherto been performed in the following manner.
To start with, when designating a delivery pallet rack position, a stacker crane accessible thereto is designated and then moved. The stacker crane comes to the designated position, and the fork of the stacker crane stretches to take out the pallet loaded with the articles from the pallet rack and transfer them onto the stacker crane. The pallet is returned to the station position by the stacker crane, wherein the pallet is placed on a conveyor for unstacking the articles. The group of article cases on the pallet are separated on the unit of article case by a case flow rack provided in a place to which the conveyor runs. Next, the articles designated by the sorter are taken out, and the articles are grouped based on a delivery request. The thus grouped articles are palletized once again to group a designated number (e.g., 50 pieces) of articles in a delivery berth and then delivered. A delivery form in this case may be configured based on the same articles or plural kinds of articles.
In this type of conventional 3-D warehouse, the number of the entrance/delivery stations is 2 at most for one stacker crane. Further, a function of the station is fixed. A lay-out of the warehouse is determined in terms of a single significance, and hence a degree of freedom in design is poor. For instance, when the stations are common to the entrance and delivery of the articles, the entrance/delivery operations eventually have to be performed separately in terms of time for preventing a confusion in operation. For this reason, the stacker crane returning from the delivery station during the delivery operation is invariably empty. The stacker crane going to the entrance station from the pallet rack during the entering operation is invariably empty. This results in such a problem that a stacking efficiency is low.
Further, the entrance/delivery stations are generally provided at the lowermost portion. It therefore takes much time for taking in and out the articles with respect to the blocks remote from the entrance/delivery stations, viz., the upper blocks in general. For this reason, the remote blocks, e.g., the blocks closer to points E and F in FIG. 18, are not available. There arises a problem in which a using efficiency declines. It is required that running and vertical movements of the stacker cranes be effected by use of powerful driving means in order to quickly transfer the articles to such remote blocks. A problem is also caused, wherein this brings about an increase in the price of equipment.
Moreover, the quick delivery of the articles is highly demanded in so-called seasonable goods such as foodstuffs and home electric products. A quicker and higher efficiency physical distribution management is desired. The conventional 3-D warehouses do not necessarily satisfy such a demand.
Besides, when the bring-in conveyor to the sorter is single as in the prior art, the feeding way is fixed. Hence, if the articles do not drop as expected, this conduces to such a problem that the articles are jammed at the terminal of the conveyor and have to be removed by human hands.
Furthermore, in spite of the fact that sorting ports are disposed on both sides of the conveyor in a conventional sorter structure, there is prepared a single line of the bring-in conveyor. Hence, this leads to a problem in which it takes a considerable time for a movement to the sorting port, and the working efficiency is poor. Besides, the conveyor running from the sorter to the discharge port is fixed in its conveying direction, there-by by causing a problem of making the working efficiency poor.